Oracle 迭代查詢 CONNECT BY PRIOR ……START WITH ……

 connect by prior start with 經常會被用到一個表中存在遞歸關係的時候。比如我們經常會將一個比較複雜的目錄樹存儲到一個表中。或者將一些部門存儲到一個表中，而這些部門互相有隸屬關係。這個時候你就會用到connect by prior start with。

 表結構：

create table TB_ORG
(
  ORGID            VARCHAR2(50) not null,
  ORGNAME          VARCHAR2(100),
  ORGPARENT        VARCHAR2(50),
)

SQL> select orgid,ORGPARENT from tb_org order by ORGid desc;

ORGID                                              ORGPARENT
-----------------                                   --------------------------------------------------
top_org                                            
newsroom                                      top_org

sjgt                                                 newsroom
bgjsyj                                             newsroom
bgjs                                                newsroom
test52                                            bgjsyj
test36                                            bgjsyj
test3                                              bgjs
test2                                              sjgt
test1                                              sjgt
tes4t1                                             bgjs

--子取父
select * from tb_org CONNECT BY PRIOR orgparent=orgid START WITH orgid='newsroom'
-----子取父變形 （）
select * from tb_org CONNECT BY PRIOR orgparent=orgid START WITH orgparent='newsroom'
--父取子（結果中沒有父這條記錄）
select * from tb_org CONNECT BY PRIOR orgid=orgparent START WITH orgparent='newsroom'
-----父取子變形（多了父這一級）
select * from tb_org connect by prior orgid=orgparent start with orgid ='newsroom'

 

 

 

注意orgid=orgparent 和orgparent=orgid

轉自：http://blog.csdn.net/kenny1985/article/details/3980583